But e-cigarette enthusiasts — "vapers" — argued that the nitrosamine levels were on par with what's in an FDA-approved nicotine patch. They worry that regulators won't make vaping products better, just more costly and harder to get.
"If their thing is, 'We can't approve this until there's proof that it's 100 percent safe, I'd say, 'Hey, people are dying while you're waiting for this proof,' " said Elaine Keller, who heads the vaper-founded Consumer Advocates for Smoke-free Alternatives Association. "It doesn't need to be 100 percent safe. It only needs to be safer than continuing to smoke."
Her group funded its own study last year. It raised $15,000 three days after asking members for donations, then tapped Igor Burstyn, an occupational health researcher at Drexel University.
He examined studies of e-cigarettes among users and in laboratory experiments, concluding that neither ingredients nor contaminants found in the vapor "pose any health concerns, and certainly not to a bystander."
"People should really pay attention to what smokers want and what they ask for," Burstyn added.
Smokers-turned-vapers are quite vocal on that count. They talk about the product with the passion of evangelists.
Janice Freeland and her son, Brad Martin, vaped at Kahuna Vapor on Tuesday and tallied up how much better they feel — and smell — since they stopped smoking two years ago. Freeland's husband switched, too, and she converted two employees at her Ellicott City Sew-Vac shop next door to Kahuna.
One of those employees, Mark Schell, 47, quit traditional cigarettes last year after more than three decades — he got hooked young. Nicotine gum didn't help, he said. Neither did patches. Vaping is less expensive than those aids or smoking, he said.
"You could get a $13 bottle of liquid that'll last you a month, or you could buy a pack of cigarettes every day for $7 a pack," said Martin, 30.
For Martin, the gadget aspect of e-cigarettes is part of the appeal. He could vape with a $15 device, but he opted for a $100 model. It has a digital display, adjustable voltage and software that tracks his usage.
What he uses is different from the e-cigarettes sold in convenience stores that must be bought repeatedly, like disposable razors, and typically look like their tobacco namesakes. The devices that vapor stores sell are reusable, look like fancy pens or metal cylinders, and can be refilled with flavored liquid to taste like just about anything.
Kahuna Vapor's "juice" comes in more than 70 flavors. Butterscotch drops. Strawberry smoothie. Pina colada. Chocolate hazelnut. The store offers tobacco flavors, too, but those aren't the most popular.
The store sells its liquid with varying amounts of nicotine, including none at all. John Mayhew, a Severn man who just switched from smoking to vaping, is stepping his nicotine levels down in hopes of getting to zero.
"I've got two kids now," said Mayhew, 29. "I need to quit. I can't afford it, either."
As Mayhew paid for his refill, other vapers played an Xbox game on the television hanging above the bar. Bowser, who co-owns the shop with his father, hopes to sell wine and beer at some point, but in the meantime it's strictly a "vape bar." Customers who want to hang out while using the shop's flavors and devices can do so for $8 an hour.
Bowser switched from smoking to vaping almost a year ago and only afterward thought to make a business of it. It's the same story with the people running other new shops in the area, the Vapers' Edge in Parkville and BmoreVapes downtown.
Ronald Ward, a lawyer who just opened the Parkville store, began vaping four years ago — which qualifies him as a grizzled veteran by the new technology's standards.
"I was three months on e-cigarettes, and I wanted to be an activist," said Ward, who had tried repeatedly to quit smoking since picking up the habit at age 12. "I wanted to fight for these products."
But now he's a vendor, and he has to be circumspect. He can't tell his customers that vaping will help them stop smoking because the FDA hasn't approved any e-cigarettes as cessation tools.
He knows that new rules could pop up, from the FDA and elsewhere. He chose his Harford Road location carefully in case e-cigarette shops are banned from areas near homes and schools.
For Penny Walker, owner of MaddCatt Vapors in Cumberland, the uncertain future is exciting and scary.
"We want to get regulated — I feel like we're in a gray area," she said. "But on the other hand, they should be well-informed guidelines."